Automatic reclosing circuit-breaker system



Oct. 9, 1923. 1,470,582

0. C. TRAVER AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed Dec. 20, 1921 Grid Potentia/ ITWVBYWtOT: v Ol'n/er C.T-a,\/e r-,

by W His Attorney Patented Oct. 9, 1923.

UNITED STATES PATENT OFFICE.

OLIVER C. TRAVER, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC AUTOMATIC RECLOSING CIRCUIT-BREAKER SYSTEM.

7 Application filed December 20, 1921.

To all whom. it may concern Be it known that I, OLIVER C. TRAVER, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Automatic Reclosing CircuitBreaker Systems, of which the following is a specification.

My invention relates to automatic reclosing circuit breaker systems, and particularly to such systems in which a circuit breaker is arranged ,to connect automatically a source of urrent to load circuit as soon as the load conditions are such that the circuit breaker can be closed without overloading the source, and has for its object the provision of a new and improved arrangement of apparatus for accomplishing this result.

In accordance with my invention, I arrange the system so that an electron dis-v charge tube is connected to the load circuit when the circuit breaker is opened and the current through the tube is varied in accord ance with the load resistance. The reclosing of the circuit breaker is governed by an electromagnetically operated device set to operate when the current through the electron discharge tube corresponds toa desired predetermined value of load resistance.

My invention will be better understood I from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is a diagram of an automatic reclosing circuit breaker system showing one embodiment of my invention; Figs. 2,3 and 4 show modifications of the embodiment shown in Fig. l; and Fig. 5 shows a characteristic current curve of an electron discharge tube which may be employed.

eferringto Fig. 1, 1 represents a circuit breaker of any suitable type which is arranged to connect a source of current 2, here shown as a direct current generator, to one side of the load circuit 3, the other side of which is grounded. The circuit breaker 1 is provided with a closing coil 4 which, when energized closes and maintains the circuit breaker in its closed osition. This closing coil may be connected to any suitable sourceof current such as the generator 2. The circuit of the closing coil 4 which is normally completed extends from the positive Serial No. 523,755.

side of the generator 2 through the contacts 5 of the overload relay 6 and the auxiliary contacts 7 on the circuit breaker 1 to ground. The overload relay 6 is provided with a winding 8 which is connected in series with the source 2 and the load circuit 3 and is so designed that it opens the contacts 5 when the load current exceeds a predetermined value. The overload relay (3 is also provided with any suitable means, such as a dash pot 9, whereby the contacts are opened either instantly or after a predetermined interval when an overload occurs on the load circuit, but are not closed until a predetermined interval after the winding 8 is deenergized. 10 represents a current limiting impedance, such as a resistor, which is arranged to be connected in series with the source 2 and the load circuit 3 when the circuit breaker is open so as to limit the current supplied to the load circuit to a very small value.

When the circuit breaker is opened, the circuit of the closing coil 4 is controlled by means of an electron discharge tube 12 which is so arranged as to effect the energization of the coil 4 when the load resistance exteeds a predetermined value.

In the particular embodiment of my invention shown in this figure, the electron discharge-tube 12 comprises a. cathode 13 of filamentary form connected in series with the resistor 10, an anode 1 1 connected to any suitable source of potential, such as the source 2 so that it'has a positive charge relative to the cathode 13 and a grid 15 interposed between the cathode and the anode and connected to the load circuit so that it has a negative charge relative to the cathode. It is evident, however, that the cathode could be heated from a separate source and a tap connection made to the load circuit or limiting resistance to establish the necessary potential of the filament. A coil 16 of a relay 17 is connected in serieswith the cathode 13 and anode l4. The relay 17 is arranged to close its contacts 18 and thereby complete the circuit of the closing coil 4 when the current through the tube drops below a predetermined value.

The operation of the arrangement shown breaker 1 in its closed position short circuits the resistor 10 and the filament 13 so that no current flows through these devices and consequently the relay 17 is deenergized.

When an overload or short circuit occurs on the load circuit 3, overload relay 6 opens its contacts 5 and deenergizes the closing coil 4. Circuit breaker 1 then opens and the resistor 10 and filament 13 are connected in series with the source 2 and the load circuit 3. A small current is now supplied to the load circuit which heats the filament 13 and since the anode 14 is connected so that it has a positive charge relative to the cathode 13, a current flows through the electron discharge tube and the winding 16 of the relay 17. Relay 17 operates and opens its contacts 18 so that the closing coil 1 is not energized when the overload relay 6 closes its contacts 5 after a predetermined interval determined by the setting of the dash pot 9.

As the load resistance increases, the potential across the load circuit increases so that the grid 15 becomes more negative with respect to the cathode 13.

The amount of load resistance that is required to close the breaker may be varied in any suitable manner as by means of the adjustable resistance 11 which is connected between the filament 13 and the load circuit 3.

Referring to Fig. 5 which shows the effect the grid potential has upon the current through an electron discharge tube which is suitable for my invention it will be seen that as the grid potential becomes more negative with respect to the cathode the current through the electron discharge tube decreases. Consequently an increase in the load resistance decreases the amount of current through the tube 12 and the winding .16. When the load resistance reaches a predetermined value, the current through the tube becomes so small that the relay 17 closes its contacts 18 and completes the circuit of the closing coil 4 to close the circuit breaker 1.

In the modification of my invention shown in Fig. 2, the filament 13 of the electron discharge tube and a resistor 19 are connected in series across the terminals of the source 2 by means of the auxiliary contacts 20 on the circuit breaker when the circuit breaker is opened. It is evident, however, that the filament 13 could be heated and the desired potential impressed thereon in any other well known manner. The grid 15 in this case is connected tothe load circuit so that it becomes more positive relative to the cathode as the load resistance increases. Otherwise, this-modification is the same as the embodiment shown in Fig. 1, except that the relay 17 is arranged to close its contacts 18 when the cur- 1,47o,ess

rent through the tube 12 is above a predetermined value instead of when it is below a predetermined value.

The operation of this modification of my invention is as follows: When a short circuit or overload occurs on the load circuit 3, the overload relay opens its contacts 5 and interrupts the circuit of the closingcoil 4. Circuit breaker 1 then opens and inserts the current limiting resistor 10 in series with the source 2 and the load circuit 3 thereby completing the circuit of the filament 13. Filament l3 heats up and current flows through the tube 12 and the coil 16 of the relay 17. \Vith a short circuit or an overload connected to the load circuit, not enough current fiows through the tube 12 to operate the relay 17. As the load resistance increases, the potential drop across the load circuit increases so that the grid 15, which is connected to the positive side of the load circuit, becomes more positive with respect to the cathode 13. Consequently, the current through the relay 17 increases with the load resistance and when the load resistance reaches a predetermined value, the current through the winding 16 is sufiicient to operate the relay and close its contacts 18 thereby completing the circuit of the closing coil 4. Circuit breaker 1 then closes and by closin its auxiliary contacts 7 completes a holding circuit for the coil 4;. The opening of the auxiliary contacts 20 on the circuit breaker opens the circuit of the tube 12 so that the relay 17 becomes deenergized.

In the arrangen'ient'shown in Fig. 1, it is evident that if the filament of a tube burns out or the circuit thereof is interrupted in any way, the coil 16 of the relay 17 becomes deenergized and the closing coil 4 is energized to reclose the circuit breaker irrespective of the load resistance. In order to overcome 'this'undesirable feature I prefer to use the modification shown in Fig. 3. In this modification the control relay 19 is constructed as a balanced relay which is normally held in its open position by a spring 20. The current that flows through the tube 12 fiows through asolenoid 21 which also tends to kee the control relay 19 in its open position. he control relay 19 is arranged to be moved into its reclosing position by a solenoid 22 which is connected in series with an electron discharge tube 23, the filament of which is shown as being connected in series with the filament 13 of the tube 12. The tube. 23 is of the type known in the art as the kenotron and consists of a cathode 24 and an anode 25. The anode is connected to the source 2 so that it is more positive than the cathode 24.

The operation of this modification of my invention is as follows: Vhcn an overload or short circuit occurs on the load circuit the circuit breaker 1 opens and inserts the re sistor 10 and the filaments 13 and 24 in series with the load circuit. The filaments 13 and 24 become heated and a current flows through each of the tubes. So long as the short circuit or overloadis connected to theload circuit, the spring 20 and the solenoid 21 are sufiicient to maintain the control relay in its open position, As the load resistance increases the potential across the load circuit increases so that the grid 15 becomes more negative with respect to the cathode 13. Consequently, .an increase in the load resistance decreases the amount of current through the tube 12 and the solenoid 21. The current through the tube 23, however, remains substantially constant since the percentage change in the total resistance connected to the generator 2 produced by the load resistance increasing from zero to its normal full load value is very small and consequently the temperature of the filament 24,,which controls the current through the tube 23, remains substantially constant. When the load resistance reaches a predetermined value the current through the solenoid 21 decreases sufficiently to allow the solenoid 22 to overcome the opposing forces exerted by the spring 20 and the solenoid 21. Control relay 19 then movesinto its closed position and completes the circuit of the closing coil 4 to reclose the circuit breaker. As soon as the circuit breaker closes the holding'circuitof the closing coil 4 is completed through the auxiliary contacts 7, and the resistor 10 and filaments 13 and 24 are short circuited. Solenoids 21 and 22 then become deenergized and the spring 20' moves the control relay 19' into its open position.

It will be noted that if either one of the filaments should burn out or the circuit thereof become broken in any way both of the solenoids 21 and 22 would be deenergized since the filaments are connected in series. Consequently, the spring 20 would maintain the control relay 19 in its open position alnd prevent the circuit breaker from being c ose a In the modification of Fig. 1 shown in Fig. 4, a second electron discharge tube 30 is used in conjunction with the tube 12 to control the reclosing of the circuit breaker. The filament 31 of theelectron discharge tube 30 is shown as being connected in series with the filament 13. It may be desirable in some cases to connect the filaments so that the filament 31 is more positive than'the filament 13. As above stated the filaments could be heated in any other suitable Way and connections made to the load circuit or current limiting resistor so as to establish the necessary potentials. The grid 15 of the tube 12 is connected to the negative side of the load circuit, which in this case is grounded and the anode 14 is connected to a suitable source of potential, such as the generator 2 so that it has a positive potential relative to the cathode 13, An impedance 32 such as a resistor is connected in series with the cathode 13 and anode 14 and the grid 33 of the electron discharge tube 30 is connected to a tap on this impedance. The anode 34 of the tube 30 is also connected to a suitable source of potential such as the generator 2 so that it has a positive potential relative to the cathode 31. The coil 35 of a relay 36 is connected in series with anode 34 and cathode 31 of the tube 30 and this relay is arranged to close its contacts 37 and complete the circuit of the closing coil 4 to close the circuit breaker 1 when the current through the tube 34 exceeds a predetermined value. v

- The operation of this modification is as follows: Under normal conditions the circuit breaker 1 is held in its closed position by the energization of the closing coil 4, the circuit of which is completed through the overload relay contacts 5 and the circuit breaker auxiliary contacts 7. The circuit breaker in its closed position short circuits the resistor 10 and the filaments 13 and 31 so that no current flows through these devices and consequently the relay 36 is deengized and the contacts 37 are opened. When an overload or short circuit occurs on the load circuit, overload relay 6 opens its contacts 5 and deenergizes the closing coil 4. Circuit breaker 1 then opens so that the resistorlO and the filaments 13 and 31 are connected in series with the source 2 and the load circuit 3. The small current which is now supplied to the load circuit heats the filaments 13 and 31. Since the anodes 14 and 34 are connected s0 that they are positive relative to the cathodes 13 and 31, respectively, currents flow through both of these tubes. The current that flows through the tube 12 also flows through the impedance 32 and the current that flows through the tube 30 flows through the coil 35 of the relay 36, but is not sufficient to operate this relay when the load resistance is below a predetermined value. As the load resistance increases the potential across the load circuit increases so that the grid 15 becomes more negative with respect to the cathode 13. Consequently, the current that flows through the tube 12 and the impedance 32 decreases and this has the effect of increasing the potential of the tap on the impedance 32 to which the grid 33 of the tube 30 is connected. This increase in potent'al of the grid 33 in turn increases the current through the tube 30 and the coil 35 of the relay 36.v It is evident, therefore that with this arrangement of tubes a cumulative action is ob- ,tained so that a very small change in the load resistance produces a very large change in the current through the coil 35. When the load resistance reaches a predetermined value the current through the tube 30 is suilicient to operate the relay 36 which closes its contacts 37 and completes the circuit of the closing coil 4 to close the circuit breaker l. The circuit breaker in its closed position completes a holding circuit for the coil 4 through the auxiliary contacts 7 so that the coil remains energized after the relay 35 opens its contacts due to the filaments l3 and 31 being short circuited by the main contacts of the circuit breaker.

it will be observed that if either filament should burn out while the circuit breaker is open the relay 36 would remain deen ergized and consequently there is no danger of a premature closing of the circuit breaker due to the burning out of a filament. Furthermore, this arrangement has the advantage that the current through the tube 30 can be limited to a safe operating value in case the load resistance should suddenly increase to a very large value before the circuit breaker closes. By constructing the tube 12 so that the current through it decreases to zero when the load resistance reaches the predetermined value at which the circuit breaker closes, it is evident that if the load resistance should increase above this predetermined value it would not increase the potential of the grid 33 of the tube 34. Consequently, the Current through the tube 30 is lim ted by the zero current of the tube 12. In this way large currents through the'tube 30. due to large increases in the load resistance, are prevented.

"While I have shown and described several embodiments of my invention, I do not desire to be limited to the exact arrangements shown and described but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is 1- 1. In an automatic reclosing circuit breaker system, the combination with a load circuit, a source of current, a circuit breaker for connecting said source to said load circuit. and closing means for said circuit breaker, of an electron discharge tube arranged to control the operation of said closing means in accordance with the load resistance when said circuit breaker is open.

2. In an automatic reclosing circuit breaker system, the combination with a load circuit, a source of current, and a circuit breaker for connecting said source to said load circuit. of an electron discharge tube having a cathode and an anode connected to said source so that the anode is-more positive than said cathode and a grid connected to said load circuit so that the potential difference between the grid and cathode varies with the load resistance, and closing means for said circuit breaker arranged to be controlled by the currentthrough said tube.

In an automatic reclosing circuit breaker system, the combination with a load circuit, a source of current, a circuit breaker for connecting said source to said load circuit, and a closing coil for said circuit breaker arranged to close said breaker upon the energization thereof, of an impedance arranged to be connected in series with said load circuit and said source when said circuit breaker is open, an electron discharge tube having a cathode and an anode connected to said impedance so that the anode is more positive than the cathode and a grid connected to the load circuit so that the grid becomes more negative with respect to the cathode as the load resistance increases, and a relay arranged to be operated to effect the energization of said closing coil when the current through said tube drops below a predetermined value.

4;. In an automatic reclosing circuit breaker system, the combination with a load circuit, a source of current, a circuit breaker for connecting said source to said load circuit, a closing coil for said circuit breaker arranged when energized to close and maintain said breaker in its closed position, a normally closed circuit for said closing coil, and means arranged to be operated by an overload on said load circuit to open said normally closedcircuit and to )revent the reclosing of said normall close circuit for a predetermined interval after the occurrence of the overload, of an impedance arranged to be connected in series with said load circuit and said source when said circuit breaker is open, an electron discharge tube having a cathode connected in series with said impedance, an anode connected to said impedance so that the anode is more positive than said cathode and a grid conncted to the load circuit so that. the grid becomes more negative with respect to the cathode as the load resistance increases, and a relay controlled by the current through said tube arranged to complete a circuit for said closing coil when the current through said tube drops below a predetermined value.

5. In an automatic reclosing circuit breaker system, the combination with a-load circuit, a source of current, and a circuit breaker for connecting said source to said load circuit, of an electron discharge tube arranged to be connected to said load circuit'when said circuit breaker is open so that the current through said tube varies in accordance with the load resistance, and closing means for said circuit breaker arranged to be ope ated b the current through said tube to close sai breaker only when thrla load resistance is above a predetermined va ue.

6. In an automatic reclosing circuit breaker system, the combination with a load circuit, a source of current, and a circuit breaker for connecting said source to said load circuit, of an electron discharge tube comprising a cathode and an anode arran d to be connected to said load circuit wfizn said circuit breaker is open so that the current through said tube decreases as the load resistance increases, a heating circuit for said cathode, closing means for said circuit breaker arranged to be operated when the c said closing breaker system, the combination with through said current through said tube drops below a predetermined value, and meansfor preventing the operation of said closing means when the heating circuit of the cathode of said tube is open.

7. In an automatic reclosing breaker system, the combination with a load circuit, a source of current, a circuit-breaker for connecting said source to said load circuit, and closing means for said circuit breaker, of a plurality of electron discharge tubes, each'having a cathode and an anode, arranged "to control jointly the operation of means in accordance with the load resistance, and a series heating circuit for the cathodes of said electron discharge tubes.

8. In an automatic reclosing circuit a load circuit, a source of current, and a. circuit breaker for connecting said source to said load circuit, of an electron discharge tube arranged to be connected to said load circuit when said circuit breaker is open so that the current throu h said tube varies in accordance with the%oad resistance, a second electron discharge tube arranged to be connected to said first mentioned tube so that current" through said second tube varies in accordance with the current through said first tube, and closing means for said circuit breaker arranged to be controlled by the current second tube so as to close said circuit breaker when the load resistance is above a predetermined value.

n an automatic reclosing circuit breaker systeii, the combination with a load circui, a source of current, and a circuit breaker for connecting said source to said loadcircuit, of an electron discharge tube arranged to be connected to said load circuit when said circuit is open so that the current through said tube varies inversely with the load resistance, a second electron discharge tube connected to said'first mentioned tube so that the current through said second tube is controlled by the current through said first mentioned tube, and closing means for said curcuit breaker-arranged to be controlled by the circuit through said second mentioned tube so as to close said circuit breaker when the load resistance is above a predetermined value.

circuit 10. In an automatic reclosing circuit breaker system, the combination with a load circuit, a source of current, and a circuit breaker for connecting said source to said load circuit, of an impedance arranged to be connected in series with said load circuit and said source when said circuit breaker is open, an electron discharge tube having a cathode and an anode connected to said source so that the anode is more positive than said cathode and a grid connected to said load circuit so that the potential difference between said grid and cathode varies with the load resistance, a second impedance connected in series with the cathode and anode of said electron discharge tube, a sec,- ond electron discharge tube having a cathode and'an anode connected to said second impedance so that the anode is more positive than said cathode and a grid connectedto said second impedance so that potential of said grid becomes more positive with' respect to cathode of said second tub'e-asthe current through said firsttube decreases, and closing means for said circuit breaker arranged to close said circuit breaker when the current through said second tube exceeds a predetermined value.

11.. In an automatic reclosing circuit breaker system, the combination with a load circuit, a source of current, and a circuit breaker for connecting said source tosaid load circuit, of an impedance arranged to be connected in series with said load circuit and said source when said circuit breaker is open, an electron discharge tube having a cathode and an anode connected to said impedance and load circuit so that the anode is more positive than said cathode and a grid connected to said load circuit so that the potential difference between said grid and cathode varies with the load resistance, a second impedance connected in series with the cathode and anode of said electron discharge tube, a second electron discharge tube having a cathode and an anode connected to said second impedance so that the anode is more positive than said cathode and a grid connected to said second impedance so that potential of said grid becomes more positive with respect to cathode of said second tube. as the current through said first tube decreases, a closing coil for said circuit breaker arranged to close said circuit breaker upon the energization thereof, and a relay connected in series with the cathode and anode of said second electron discharge tube and arranged to complete a circuit for said closing coil to close said circuit breaker when the current through said second tube exceeds a predetermined value.

In witness whereof, I have hereunto set my hand this 19th day of December, 1921.

OLIVER C. TRAVER. 

